With the advent of the widespread introduction of electronic circuits into mass produced vehicles, such as automobiles and aircraft, and other products such as military equipment including projectiles, there has arisen a need for reliable, inexpensive vibration mounted for such circuits in order to protect their integrity against various shocks which are encountered during normal vehicle operation.
In the design of vibration mounts based on prior art teachings, the damping friction is normally raised as much as possible so as to reduce and limit Tmax, the maximum transmissivity, or, in other words, the maximum displacement of the mounted mass M per unit displacement of the base.
There are also known vibration mounts incorporating a body of wire mesh or similar material. Flexing of such material provides Coulomb friction resistance up to a predetermined maximum at which the wire mesh becomes compressed so that both friction and stiffness are increases significantly.
The wire mesh mount has a number of deficiencies:
1. It is capable of dissipating only limited energy unless the friction force is greatly increased. Such an increase in friction can result in significant forces being transferred to the supported mass.
2. The supported mass does not normally return to a defined rest position.
3. After a time, the wire mesh may become compressed and set and thus behave as a rigid mount. In order to overcome this problem, an additional spring is sometimes associated with the mesh. However, the characteristics of the spring often outweigh the characteristics of the wire mesh and its increased stiffness.
4. Perhaps most importantly, the behavior of the wire mesh spring mount cannot be calculated precisely because it depends on the relative orientation and tightness of the individual wires in the mesh which tend to change over time as a a function of the use thereof.